Media center pc with NotSoNew hardware

Well, for starters, i'm not even running windows media center on it!
I assembled half a year ago a computer to watch some dvds and divx on my tv 16:9 screen in my living room. The tv itself is not so good as it sounds, because it has a cheap CRT screen, so i couldn't bore much to build a great computer for high defenition movies, it would be useless as my tv wouldn't "render" all the detail.
The machine itself is a celeron 2ghz, with a seagate barracuda 40 GB hdd 7200rpm, 512mb DDR and a geforce 4 mx 440 agp 8X with 128 MB DDR.
The problem is, when playing movies with higher resolutions such as 1280x720 (not sure about the resolution), the movie playback sucks a lot, because the framerate lengh lags behind the sound from the movie file.
Will a better cpu help it? I'll have a pentium 1.7 ghz cpu next week, that is better than the celeron (not by much i know) and i'm holding my thingers that it will help a bit.

I still remember when playing "The Matrix" movie on my amd k6 and "Gladiator", same thing happened. It is a annoying problem really :s

A better CPU will help. I dunno if it'll actually solve the problem. Why are you running 720p on a SD CRT?

Well, yeah, it's not the greatest CPU in the world

It might do. I've been toying with the idea of sticking a 6600GT in mine, with PureVideo, as a video accelerator.

I suspect that the decrease in load won't have *that* much of an effect, though.